JP4329551B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus for receiving, for example, digital terrestrial broadcasting.

  At present, digital broadcasting using MPEG-2 Systems (ISO / IEC 13818-1), which is one of video and audio compression transmission systems, has been put into practical use.

  In digital broadcasting, system information necessary for receiving broadcasts other than content information such as audio and video is included in a transport stream defined by MPEG-2 Systems and transmitted. Such system information is described and transmitted in various tables called PSI (Program Specific Information) defined by MPEG-2 Systems and SI (Service Information) defined by various digital broadcasting standards.

  In ISDB-T, which is a standard for digital broadcasting in Japan, it is stipulated that information indicating the content of a service or event being broadcast is included in system information and transmitted. For example, ISDB-T stipulates that information indicating the contents of services and events being broadcast is described in tables called SDT (Service Description Table) and EIT (Event Information Table) in SI. (See Non-Patent Documents 1 and 2).

  In digital broadcasting using MPEG-2 Systems, the content unit provided by news or dramas is generally called an “event”, and the unit in which multiple events are organized in the time direction is called a “service”. It is called. That is, an event corresponds to a “program” in the conventional analog broadcast, and a “service” corresponds to a “broadcast channel” such as NHK synthesis and NHK education in the conventional analog broadcast. Then, one or a plurality of services are multiplexed and broadcast on a single transport stream defined by MPEG-2 Systems.

"Transmission method of digital terrestrial broadcasting ARIB STD-B10 3.7 version", the radio industry, established on June 5, 2003, September 19, 1997 "Transmission method for digital terrestrial broadcasting ARIB STD-B30 version 1.1", the radio industry, established on May 31, 2001, July 29, 2003

  By the way, in digital broadcasting in which broadcast signals are distributed from broadcast satellites or communication satellites, etc., it is assumed that reception is performed while the receiver is fixed at a predetermined position. It does not move once set, but in terrestrial digital broadcasting in which broadcast signals are distributed from terrestrial broadcast stations, mobile reception is possible while receiving movement, and the receivable broadcast stations depend on the movement position. Change. Therefore, when mobile reception is performed, the service may not be received due to a change in the reception environment. For example, if a broadcast signal is blocked by a mountain or building and cannot be received topographically, or if it cannot be received geographically such as moving outside the reception area of the service being received, the service is interrupted or It may be cut off.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a digital broadcast receiving apparatus that can perform stable reception even when the reception environment changes.

  The digital broadcast receiving apparatus according to the present invention includes a plurality of antennas and a plurality of demodulation units, receives and demodulates broadcast signals by diversity using the plurality of antennas and the plurality of demodulation units, and converts the broadcast signals into the broadcast signals. Receiving demodulation means capable of demodulating the modulated digital data stream; and content decoding means for decoding the content information contained in the digital data stream demodulated by the receiving demodulation means.

  During normal reception, the reception demodulation means receives and demodulates a broadcast signal of an arbitrary channel by diversity using a plurality of antennas and a plurality of demodulation units, and outputs a first digital data stream.

The reception demodulating unit divides the plurality of antennas and the plurality of demodulation units into two groups when the reception state of the broadcast signal of the arbitrary channel received during the normal reception is bad. Using the antenna and demodulator of the group, the broadcast signal of the arbitrary channel received during the normal reception is received and demodulated and the output of the first digital data stream is continued, and the other group Scan all the frequencies of other channels that are different from the above-mentioned arbitrary channels using the antenna and demodulator , identify the channels that can be newly received and the channels that cannot be received, and It selects a channel based on the system information of the first digital data stream from, subjected to reception and demodulation of a broadcast signal of the channel , And it outputs a second digital data stream.

In the digital broadcast receiving apparatus according to the present invention, during normal reception, reception and demodulation are performed by diversity using a plurality of antennas and a plurality of demodulation units, and when the reception state is poor, some antennas and demodulation units are used. Scan all the frequencies of other channels that are different from the normal reception channel, identify the newly receivable channel and the unreceivable channel, and select the normal channel from the receivable channels. A channel is selected based on the system information of the digital data stream at the time of reception, and the broadcast signal of the channel is received and demodulated. As a result, the digital broadcast receiving apparatus according to the present invention can always provide the user with stable service and event information even when the reception environment changes with movement.

  Hereinafter, as an embodiment of the present invention, an apparatus in which the present invention is applied to a terrestrial digital broadcast receiving apparatus that receives and demodulates a terrestrial digital broadcast signal and outputs a video signal and an audio signal will be described.

  The digital terrestrial broadcast receiving apparatus described below is an apparatus corresponding to the digital terrestrial broadcast standard (ISDB-T) adopted in Japan. In other words, a broadcast signal broadcast from a broadcast station is a transmission path code that performs Reed-Solomon encoding, convolutional encoding, and time and frequency interleaving on a transport stream defined by MPEG-2 Systems (ISO / IEC 13818-1). Next, the signal is subjected to OFDM modulation processing such as IFFT (Inverse Fast Fourier Transform) calculation and guard interval addition processing.

(overall structure)
FIG. 1 shows a block diagram of a digital terrestrial broadcast receiving apparatus 10 to which the present invention is applied.

  As shown in FIG. 1, the terrestrial digital broadcast receiving apparatus 10 includes a first antenna 11, a second antenna 12, a first reception / demodulation unit 13, a second reception / demodulation unit 14, and diversity. A control unit 15, a TS decoding unit 16, an audio decoding unit 17, a video decoding unit 18, an OSD (on-screen display) processing unit 19, and a system control unit 20 are provided.

  The first antenna 11 and the second antenna 12 are antennas that receive terrestrial digital broadcast signals broadcast from broadcast stations. The first antenna 11 and the second antenna 12 are spatially arranged such that the spatial arrangement position, the direction of directivity, and the like are changed from each other, and reception and demodulation by diversity can be performed efficiently.

  The first reception / demodulation unit 13 receives an RF signal received by the first antenna 11, generates an IF signal from the RF signal, and OFDM-demodulates the IF signal. The second reception / demodulation unit 14 receives an RF signal received by the second antenna 12, generates an IF signal from the RF signal, and OFDM-demodulates the IF signal.

  Specifically, the first reception / demodulation unit 13 and the second reception / demodulation unit 14 frequency-convert the RF signal by a local oscillator and a multiplier that generate the same reference signal as the center frequency of the channel selection channel. Thereafter, the IF signal is generated by filtering with a band-pass filter. The first reception / demodulation unit 13 and the second reception / demodulation unit 14 subsequently perform A / D conversion processing, digital orthogonal demodulation processing, FFT operation processing, carrier demodulation processing, frequency and time on the IF signal. By performing deinterleaving, Viterbi decoding processing, layer processing, transport stream generation processing, Reed-Solomon decoding processing, etc., OFDM demodulation processing and transmission path decoding processing are performed. The first reception / demodulation unit 13 and the second reception / demodulation unit 14 perform the above OFDM demodulation process and transmission path decoding process, and thereby output the transport stream that has been modulated to the selected channel. Can do.

  Here, the first reception / demodulation unit 13 and the second reception / demodulation unit 14 are capable of independent reception and demodulation operations (hereinafter referred to as single reception operations), respectively, and the first reception. Reception / demodulation operation (hereinafter referred to as diversity reception operation) by the joint operation of both the demodulator 13 and the second receiver / demodulator 14 is possible. When a single reception operation is performed, the first reception / demodulation unit 13 and the second reception / demodulation unit 14 can receive and demodulate broadcast signals from different channels, so that two transports A stream will be output. In the case of performing a diversity reception operation, the first reception / demodulation unit 13 and the second reception / demodulation unit 14 are tuned to the same channel, receive a broadcast signal of one channel, and generate one transport stream. Will be output.

  Note that any method may be adopted as the diversity method. Here, for example, a diversity method such as a channel level combining method can be adopted.

  The diversity control unit 15 controls switching between the diversity reception operation and the single reception operation. The diversity control unit 15 performs signal synthesis and switching control performed by the first and second reception / demodulation units 13 and 14 and output control of one generated transport stream during the diversity reception operation. Further, the diversity control unit 15 performs output control of the two transport streams output from each of the first and second reception / demodulation units 13 and 14 during the single reception operation. The transport stream output from the diversity control unit 15 is input to the TS decoding unit 16.

  The TS decoding unit 16 interprets a PID (Packet ID) attached to the header of the TS packet, and the TS packet separates the input transport stream into audio data, video data, or system information. The TS decoding unit 16 supplies the payload portion to the audio decoding unit 17 if the TS packet is a packet of audio data, and supplies the payload portion to the video decoding unit 19 if the TS packet is a packet of video data. If the TS packet is a system information (PSI and SI) packet, the payload portion is supplied to the system control unit 20.

  Also, when a plurality of services are included in the decoded transport stream, the PID is interpreted, and only the audio data and video data TS packets related to the selected one service are extracted.

  The audio decoding unit 17 performs a decoding process on the input compressed audio data, and generates an audio signal having a predetermined audio format. The audio signal decoded by the audio decoding unit 17 is supplied to an audio output device or a recording device (not shown) via an audio output terminal.

  The video decoding unit 18 performs a decoding process on the input compressed video data, and generates a video signal having a predetermined video format. The video signal decoded by the video decoding unit 18 is supplied to the OSD processing unit 19.

  The OSD processing unit 19 generates, for example, a program guide information providing screen, various selection screens, subtitle data, etc. (OSD (on-screen display) images) generated by the system control unit 20 from the video signal generated by the video decoding unit 18. To synthesize. The video signal decoded by the video decoding unit 18 is supplied to a display device or recording device (not shown) via a video output terminal.

  The system control unit 20 receives an operation input by a user and performs various controls on the reception / demodulation units 13 and 14 and the diversity control unit 15. For example, the reception demodulation units 13 and 14 monitor the reception state, select channels for reception and demodulation, and the like.

  Further, the system control unit 20 interprets the system information (PSI / SI) separated by the TS decoding unit 16 to generate an OSD image such as a program guide information screen, and performs an operation based on the program guide information screen. Switches services and events to be output according to input.

(Reception operation)
Next, the receiving operation of the terrestrial digital broadcast receiving apparatus 10 will be described.

  First, at the time of normal reception, an arbitrary event is selected based on the EIT in which information related to the event (event ID, event name, event start time, duration, progress of the event, etc.) is described. When an event is selected by the user, the system control unit 20 provides information (service ID, service name, etc.) regarding the service provided in the transport stream, and in which transport stream the service is provided. The event is provided with reference to the NIT in which the physical reception conditions (channel number, center frequency, etc.) of the SDT in which the information and the like are described and the channel including the transport stream are described Identify the services and channels that are active.

  When receiving a command to start receiving an event selected by the user, the system control unit 20 causes the first reception / demodulation unit 13 and the second reception / demodulation unit 14 to tune the specified channel. A diversity reception operation is performed. For this reason, the diversity control unit 15 outputs one transport stream transmitted to the specified channel. Further, the system control unit 20 causes the TS decoder 16 to extract only the TS packet of the specified service, and supplies the extracted TS packet to the audio decoding unit 17 and the video decoding unit 18. Therefore, the audio decoding unit 17 and the video decoding unit 18 output the audio signal and video signal of the selected event.

  Furthermore, the system control unit 20 always monitors C / N, BER (Bit Error Rate), etc., which are parameters of the reception state, during the normal reception processing as described above, and changes in the reception state. As shown in FIG.

  The system control unit 20 always determines whether the reception state is bad during normal reception processing (step S1). Whether the reception state is bad is determined by detecting the S / N ratio of the received signal or by detecting the error rate of the transport stream, for example. If it is determined in step S1 that the reception state is bad, the system control unit 20 performs the subsequent process of step S2.

  Subsequently, in step S2, the system control unit 20 changes the operations of the first reception / demodulation unit 13 and the second reception / demodulation unit 14 from the diversity reception operation to the single reception operation. The unit (here, the first receiving / demodulating unit 13) continues to receive and demodulate the currently selected channel and service (step S2). Therefore, in the terrestrial digital broadcast receiving apparatus 10, even during the search process, the service output during normal reception continues to be output without interruption.

  Subsequently, in step S3, the system control unit 20 scans all the frequencies of other receivable channels with respect to the other reception / demodulation unit (in this case, the second reception / demodulation unit 14). Then, a service that can be newly received along with the movement and a service that cannot be received along with the movement are specified.

  Subsequently, in step S4, a desired channel is selected from the channels detected in step S3, and is switched to the channel that was output during normal reception.

  For example, the system control unit 20 selects the same event (broadcast content) as that of the channel and service that are single-received in step S2. This determination of the same event can be made based on the network ID (network_id) defined in the NIT. For example, in a single frequency network (SFN) that transmits a broadcast wave at the same frequency in each area, one network ID is provided for a transmission master that is a unit in which the same broadcast content is broadcast in one area. Assigned. Therefore, for example, when a certain broadcaster A broadcasts the entire Kanto area, installs relay stations in places in the Kanto area, and provides the same broadcast content including commercials and additional information, It becomes a transmission master and can be selectively received by a network ID.

  Further, when receiving across areas such as mobile reception, the same affiliated network as the broadcaster that has been received may be received. Judgment of the same series can be made by affiliation_id (sequence identification information) of BIT (Broadcaster Information Table). With this series identification information, for example, when broadcaster A provides broadcast waves by relaying to the Tokai area in addition to the entire Kanto region, replacing commercials, and assigning a different network ID However, the user can receive the same broadcast content (relay).

  In addition, an event having a high relevance to an event that is single-received may be selected. Then, for example, when the reception status of a baseball broadcast receiving a single signal is deteriorated, the baseball broadcast is automatically switched to another baseball broadcast based on EIT, etc., so that the user can save time and effort to switch channels. It also saves you the trouble of searching for the program you want to watch.

  Further, if an event is selected based on a priority order registered in advance by the user, for example, if a sports program cannot be received, it is possible to switch to a user's preference so as to receive a song program.

  Subsequently, in step S5, the system control unit 20 performs diversity reception of the channel selected and switched in step S4 using the first reception / demodulation unit 13 and the second reception / demodulation unit 14.

  When the process of step S5 is completed, the system control unit 20 returns to normal reception and monitors the reception state of diversity reception (step S1).

  As described above, the digital broadcast receiving apparatus 10 performs diversity reception using a plurality of antennas and a plurality of reception / demodulation units during normal reception, and always monitors the reception state. During the search process, the multiple antennas and multiple reception / demodulation units used for diversity reception are divided into two, and the reception and demodulation of the channels that have been received so far continue with one antenna and the reception / demodulation unit. The other antenna and the reception / demodulation unit scan all frequencies of other channels.

  Thus, even when the reception state changes with movement, the user can always acquire information such as stable services and events.

  In the digital broadcast receiving apparatus 10 described as the best embodiment, an example in which there are two antennas and two reception / demodulation units has been shown. However, diversity reception is not limited to two antennas, etc. A configuration of four is also possible. If there are more than two antennas and receiver / demodulators, divide them into two groups during the search process, use one group to continue the output of the currently received service, and use the other as another service. Used for searching. Therefore, the present invention can also be applied to a digital broadcast receiving apparatus that performs diversity reception using three or more antennas and a reception / demodulation unit.

It is a block diagram of a terrestrial digital broadcast receiving apparatus to which the present invention is applied. It is a flowchart which shows operation | movement of a terrestrial digital broadcast receiver.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Terrestrial digital broadcast receiver, 11 1st antenna, 12 2nd antenna, 13 1st reception / demodulation part, 14 2nd reception / demodulation part, 15 Diversity control part, 16 TS decoding part, 18 Video decoding Section, 19 OSD processing section, 20 system control section

Claims (8)

In a digital broadcast receiver that receives a broadcast signal of a digital broadcast,
It has a plurality of antennas and a plurality of demodulation units, and receives and demodulates the broadcast signal by diversity using the plurality of antennas and the plurality of demodulation units, and demodulates the digital data stream modulated on the broadcast signal Receiving demodulation means capable of
Content decoding means for decoding content information contained in the digital data stream demodulated by the reception demodulation means,
The reception demodulation means is
During normal reception, a broadcast signal of an arbitrary channel is received and demodulated by diversity using a plurality of antennas and a plurality of demodulation units, and a first digital data stream is output,
When the reception state of the broadcast signal of the arbitrary channel received during the normal reception is poor, the plurality of antennas and the plurality of demodulation units are divided into two groups, and the antenna and the demodulation unit of one group To receive and demodulate the broadcast signal of the arbitrary channel that was received at the time of normal reception and continue output of the first digital data stream, and to set the antenna and demodulator of the other group Scan all the frequencies of other channels that are different from the above-mentioned arbitrary channel, identify the newly receivable channel and the unreceivable channel, and select the first digital signal from the receivable channels. selects a channel based on the system information of the data stream, it performs reception and demodulation of a broadcast signal of the channel, the second digital de Digital broadcast receiving apparatus for outputting data stream. 2. The digital broadcast receiving apparatus according to claim 1, wherein the reception demodulating means selects a channel of the same event as that of the first digital data stream based on network identification information of the first digital data stream. 2. The digital broadcast receiving apparatus according to claim 1, wherein the reception demodulating unit selects a channel of the same sequence as the first digital data stream based on the sequence identification information of the first digital data stream. 2. The digital broadcast receiving apparatus according to claim 1, wherein the reception demodulating unit selects a channel of an event highly relevant to the event of the first digital data stream based on system information of the first digital data stream. 2. The digital broadcast receiving apparatus according to claim 1, wherein the reception demodulating means selects an event channel corresponding to a priority order of events registered in advance based on system information of the first digital data stream. 2. The digital broadcast receiving apparatus according to claim 1, wherein the reception demodulating means changes a spatial arrangement position and a directivity direction between an antenna of one group and an antenna of the other group. The broadcast signal is a terrestrial signal that is orthogonal frequency division multiplexed,
The digital broadcast receiver according to claim 1, wherein the demodulator demodulates the orthogonal frequency division multiplex modulation signal. The digital data stream is a digital broadcast receiving apparatus according to claim 7, wherein a transport stream defined in ISO / IEC 13818-1.

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